CN101603819B - Real-time measurement method for wood deformation microstructure characteristics - Google Patents
Real-time measurement method for wood deformation microstructure characteristics Download PDFInfo
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- CN101603819B CN101603819B CN 200910089770 CN200910089770A CN101603819B CN 101603819 B CN101603819 B CN 101603819B CN 200910089770 CN200910089770 CN 200910089770 CN 200910089770 A CN200910089770 A CN 200910089770A CN 101603819 B CN101603819 B CN 101603819B
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Abstract
The invention discloses a real-time measurement method for wood deformation microstructure characteristics. The method comprises the following steps: 1) loading wood to be detected; 2) magnifying a area to be detected through a microscopic unit in the loading process; 3) acquiring image information through an image acquisition unit and then working out the X-axis length X0-Xn and the Y-axis length Y0-Yn of every cell on a loading surface at each image acquisition moment through an image processing unit; 4) calculating the pressure or tensile strain Epsilonxn and Epsilonyn of single cells on an X axis and a Y axis according to the X-axis length X0 and the Y-axis length Y0 of each cell before deformation, as well as the X-axis length Xn and the Y-axis length Yn of each cell after deformation, wherein Epsilonxn = (Xn-X0)/Xn, and Epsilonyn = (Yn-Y0)/Yn; and 5) averaging the pressure and tensile strain Epsilonxn and Epsilonyn of all single cells in the area to be detected magnified through the microscopic unit so as to obtain the pressure and tensile strain Epsilonx and Epsilony of a whole characterized wood on the X axis and the Y axis. The method can measure micro-area tissue and cell strain to realize micro-area deformation quantization, and can monitor micro-area defects.
Description
Technical field
The present invention relates to mechanical strength performance and deformation microstructure characteristics method for real-time measurement such as compression of a kind of timber and composite wooden material or stretching.
Background technology
Timber and composite wooden material are in production and processing and use, inevitably can run into mechanical behaviors such as compression or stretching, detecting for the mechanical property of material is to guarantee subsequent product quality and the key of rationally using thereof, but this mechanical behavior is all still unintelligible to material monolithic Effect on Performance situation to the performance of material or product and micromechanism influence and microstructure characteristic.
For present detection means, mainly detect based on single macro-mechanical property.This detection means has many defectives and shortcoming:
1, only judging the performance of wood materials with the macromechanics behavior, is the deficiency that the performance of material own is grasped;
2, only can understand the result of mechanics of materials behavior, and not know to form the reason of this mechanical behavior;
3, testing process can not take in influence factors such as the temperature of measured material, water percentage;
4, the strain that obtains of testing process is the mean strain of material monolithic, can not embody the strained situation of material different tissues structure; Can not reaction wood each several part structure and integrated stress, strain relation;
5, for this heterogeneity material with anisotropic of timber, the strain result who obtains is single, can not truly reflect the ess-strain result of each institutional framework of timber;
6, after detection finishes, the bounce situations of measured material can not be in time obtained, the unrelieved stress of measured material can not be analyzed.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of real-time measurement method for wood deformation microstructure characteristics, can online in real time measures the microstructure characteristic and the mechanical property of material deformation.
In order to address the above problem, the invention provides a kind of real-time measurement method for wood deformation microstructure characteristics, comprise the steps:
1) measured material is loaded;
2) in loading procedure, amplify zone to be measured by micro-unit;
3), calculate in each image acquisition X-axis length X of each cell of loaded surfaces constantly by graphics processing unit by after the image acquisition units images acquired information
0～X
n, Y-axis length Y
0～Y
n, as the deformation situation data of measured material in the loading procedure;
4) according to the X-axis length X before each cytomorphosis
0With Y-axis length Y
0, and cytomorphosis after the X-axis length X
nWith Y-axis length Y
nCalculate pressure or the stretching strain ε of individual cells in X-axis and Y-axis
XnAnd ε
Yn, ε
Xn=(X
n-X
0)/X
n, ε
Yn=(Y
n-Y
0)/Y
n, (n=1,2,3......N);
5) will be by all individual cells in the zone to be measured of micro-unit amplification at the pressure or the stretching strain ε of X-axis and Y-axis
XnAnd ε
Yn, averaging obtains ε
xAnd ε
y, represent the pressure or the stretching strain of measured material integral body on X-axis and Y-axis,
Preferably, in described graphics processing unit calculates, also comprise the steps:
3.1) calculate at the tissue of all kinds of entity cell of each image acquisition moment loaded surfaces cell wall and make a gesture of measuring A
i(i=0,1,2 ..., I), as the deformation situation data of measured material in the loading procedure;
4.1) make a gesture of measuring A according to the tissue before the cytomorphosis
0Make a gesture of measuring A with the tissue after the distortion
iCalculate the whole strain stress of measured material
A, ε
A=(A
i-A
0)/A
i
Preferably, after mechanical behaviors such as stretching or compression finish, also comprise the steps:
5) take measured material continuously to the complete halted state of this measured material deformation resilience by described image acquisition units;
6) any one integral thickness or length L constantly after described graphics processing unit calculating measured material pressurized or the tension
kThereby, calculate springback capacity R and rebound degree R
r, R=L
k-L
0, R
r(%)=(L
k-L
0) * 100/L
0Wherein, k=0,1,2 ..., K, the moment that " 0 " representative test has just finished.
Preferably, in described measuring process the temperature of measured material is controlled at certain scope.
Preferably, in described measuring process the water percentage of measured material is controlled at certain scope.
Preferably, described loading comprises: stretch, compression, crooked, reverse or shear.
The present invention has following advantage:
1, the present invention combines continuous mechanical test process with the dynamic structural change of timber, can reflect the relation between the variation of timber or composite wooden material mechanical property and microstructure characteristic in real time.
2, the present invention can set up two-dimentional relation between the two arbitrarily, and reach real real-time " prison " and " survey " synchronous fully between mechanics loading procedure, material property data result, microstructure change image and the time data point.
3, the present invention can measure the tissue and the cell strain of microcell, realizes that the microcell distortion quantizes; Can monitor the microcell defective.
4, the present invention can test the relation between timber or composite wooden material mechanical property and the microstructure change, can quantize simultaneously distortion of materials bounce situations behind the mechanics loading procedure.
5, the present invention extends to dynamic mechanical test in low temperature or the high temperature category, can set up the relation between temperature and mechanical property and the microstructure change.
6, the present invention extends to dynamic mechanical test in the water percentage variation category, can set up the relation between water percentage and mechanical property and the microstructure change.
7, the present invention has adopted automatic focusing system, can effectively improve the image acquisition precision, shortens image acquisition at interval.
8, the present invention can realize computer full-automation operation, avoids artificial control and each system to separate the error that control is easily caused.
9, resulting stress-strain curve of the present invention and microscale deformation mechanism can be caught the key of wood materials and composite wooden material ductility and intensity.
10, of the present invention applied widely, mechanics loaded load wide ranges such as compression or stretching are suitable for
The sample of all kinds/shape and size is studied, and comprises solid wood material, composite wooden material, other timber derived products etc.
Description of drawings
Fig. 1 is a structural representation of the present invention;
Fig. 2 is the synoptic diagram of measured material of the present invention.
Embodiment
As shown in Figure 1, the present invention includes: loading unit 1, temperature-controlled box 3, sensor 4, computing machine 5 (being graphics processing unit), optical microscope 6, digital camera 7 and video camera 8.Loading unit 1 be used for measured material 2 compress, stretch or crooked, mechanical behavior such as shear, reverse.Temperature-controlled box 3 links to each other with computing machine 5 with tension and compression unit 1, is used to control the temperature (theoretical category-140～600 ℃) of timber to be checked.Optical microscope 6 links to each other with digital camera 7, video camera 8 and computing machine 5, is used for the collection of pressurized or tension measured material surface deformation image.3 cover sensors 4, covers link to each other with drilling depth system 12 in the loading unit 1, are used to measure the whole displacement of measured material 2; One cover links to each other with Load Control (pressure control or control draw etc.) system 13, measurement load value (pressure or pulling force etc.); One cover links to each other with conducting-heat elements (as the heat conduction briquetting or the folder etc. that stretches) 11, is used for the temperature of temperature-controlled box control measured material 2.Digital camera 7 all links to each other with computing machine 5 with video camera 8, is used for the data acquisition of stress and deformation map picture.Computing machine 5 is used to receive the detection data and the view data of drilling depth system 12, mechanics control system 13, digital camera 7 and video camera 8, and obtain the strain information and the springback capacity of described measured material by computed in software according to the displacement data result, obtain the real-time microstructure change result of stress-strain diagram and measured material simultaneously.
As shown in Figure 1, optical microscope 6 can be normal optical three order biological microscopes, form by spotlighting system 61, eyepiece 62, object lens 63, objective table 64 and focus adjusting mechanism, and link to each other with video camera 8, be used for the collection of stressed wood surface deformation map picture with digital camera 7; Wherein, focus adjusting mechanism is an autofocus system 65, is arranged on the optical microscope, and an end connects computing machine 5, is used to control the focal adjustments of optical microphotograph endoscope objective lens 63, by the interval time of computing machine 5 control focusing.
As shown in Figure 1, loading unit 1 is made up of conducting-heat elements 11, drilling depth system 12, load control system 13, cooling system 14, be used for to timber 2 to be checked compress, mechanical behavior such as stretching or bending; Wherein, cooling system 14 is divided into water-cooled and cold two covers of nitrogen, water-cooled is used for loading unit conducting-heat elements 11 and load control system 13 by high temperature cool to room temperature state, nitrogen colod-application in loading unit conducting-heat elements 11 drop to the state of low temperature by room temperature, thereby the temperature of control measured material.
The present invention is owing to adopt autofocus system 65 to regulate the focal lengths of the object lens 63 of optical microscopes 6 in real time automatically, thereby can effectively improve the image acquisition precision, shortens image acquisition at interval.In addition, the present invention is owing to adopt video camera 8, and overall dimensions such as integral thickness that can the stressed measured material of Real Time Observation or length change, thereby calculates the springback capacity and the rebound degree of stressed back any time measured material by the computing machine 5 that is attached thereto.Among the present invention, focusing can be adopted conventional automatic focusing method automatically.
Concrete determination step is as follows, as shown in Figure 1:
1) at first measures the radial dimension L of measured material 2
R, tangential size L
T, longitudinal size L
L(as shown in Figure 2), be input in the computing machine 5, as the raw data of this measured material;
2) measured material 2 is positioned on the loading unit 1, in computing machine 5, sets parameters such as maximum weighted (compression or stretching etc.) load, maximum compression rate (or extensibility, amount of deflection), loading velocity;
3) select the suitable object lens 63 of multiple on optical microscope 6, adjust to reasonable focal length with autofocus system 65, it is complete to make measured material 2 surfaces be clear picture in digital camera 7 and video camera 8; In computing machine 5, set the digital camera photo opporunity at interval, as 5sec, 10sec etc.; Set the automatic focusing time interval of autofocus system 65 simultaneously, the photo opporunity of setting with digital camera is identical at interval, and automatic focusing finishes before guaranteeing to take pictures at every turn;
4) the measured material finishing temperature is set in measured material 2 intensifications or cooling if desired earlier in computing machine 5, and needs to open temperature-controlled box 3 switches in mensuration preceding ten minutes (shortest time) of beginning, makes measured material 2 progressively heat up (or cooling) to design temperature;
5) while start-up loading unit 1, digital camera 7, video camera 8, automatic focusing system 65 begin test;
6) computing machine 5 obtains the size of real-time loaded load δ by sensor 4 control load control system 13; Obtain the real-time displacement data of measured material by drilling depth system 12, computing machine 5 calculates the real-time strain stress of measured material
BObtain measured material surface real-time deformation image clearly by digital camera 7 and video camera 8; Above data are sent in the computing machine 5 in real time until end of test (EOT);
7) after the end of test (EOT), rapidly measured material is taken off from loading unit 1, lie in and aim at the object lens center on the optical microscope objective table, continue to take the stressed whole measured material in back that finishes continuously to a couple of days with video camera 8, the image that video camera 8 is taken is input in the computing machine 5 in real time;
8) view data passed back according to digital camera 7 of computing machine 5 utilizes two kinds of methods by the image calculation strain to calculate the real-time X-axis strain stress of measured material
x, the Y-axis strain stress
y, whole strain stress
A, and the real-time strain stress that it and the displacement data that obtains by drilling depth system 12 are calculated
BContrast;
9) view data passed back according to video camera 8 of computing machine 5 calculates any one thickness (or length) L constantly of the stressed back of measured material
k, utilize formula to calculate pressurized (or tension) back measured material at any one springback capacity R constantly, R=L
k-L
0And rebound degree R
r, R
r(%)=L
k-L
0) * 100/L
0Wherein, k=0,1,2 ..., K, the moment that " 0 " representative test has just finished.
By the said determination step, just can access the stress-strain curve of material in whole loading procedure, obtain compression (or stretching etc.) the mechanical property characterization result of material, for example, elastic deformation stage, plastic yield stage, yield point, failure stage, and corresponding with it material microstructure deformation map picture.
In the said determination step, loading unit 1, temperature-controlled box 3, digital camera 7, video camera 8, autofocus system 65 are by computing machine 5 unified controls, run-in synchronism, data that each mechanism obtains also send back in the computing machine 5 in real time, like this, each mechanism's gained load, temperature, strain and view data all can be that object of reference is set up two-dimentional relation the time more than.
In addition, in above-mentioned measuring process, the water percentage of measured material 2 can also be controlled at certain scope, change in the category, set up the relation between water percentage and mechanical property and the microstructure change thereby dynamic mechanical test is extended to water percentage.
In addition, the present invention has comprised three kinds and has measured strain process, calculates mean strain ε thereby 1. utilize differential pick-up to measure average deformation
BMethod, 2. by each component units of image measurement (be cell in the timber) X-axis deformation and Y-axis deformation, and then calculate measured material integral body X-axis and Y-axis mean strain ε
x, ε
yMethod, the 3. variation of making a gesture of measuring by the tissue of image measurement component units entity part (entity part in the timber is a cell membrane), thus calculate measured material ensemble average strain stress
AMethod.Three kinds of method gained data can compare and complementation.
In sum; being preferred embodiment of the present invention only below, is not to be used to limit protection scope of the present invention, therefore; all any modifications of being done within the spirit and principles in the present invention, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. a real-time measurement method for wood deformation microstructure characteristics is characterized in that, comprises the steps:
1) measured material is loaded;
2) in loading procedure, amplify zone to be measured by micro-unit;
3), calculate in each image acquisition X-axis length X of each cell of loaded surfaces constantly by graphics processing unit by after the image acquisition units images acquired information
0～X
n, Y-axis length Y
0～Y
n, as the deformation situation data of measured material in the mechanical test process;
4) according to the X-axis length X before each individual cells distortion
0With Y-axis length Y
0, and cytomorphosis after the X-axis length X
nWith Y-axis length Y
nCalculate pressure or the stretching strain ε of individual cells in X-axis and Y-axis
XnAnd ε
Yn, ε
Xn=(X
n-X
0)/X
n, ε
Yn=(Y
n-Y
0)/Y
n, (n=1,2,3......N);
5) will be by all individual cells in the zone to be measured of micro-unit amplification at the pressure or the stretching strain ε of X-axis and Y-axis
XnAnd ε
Yn, averaging obtains ε
xAnd ε
y, represent the pressure or the stretching strain of measured material integral body on X-axis and Y-axis,
2. the method for claim 1 is characterized in that, in described graphics processing unit calculates, also comprises the steps:
3.1) calculate at the tissue of all kinds of entity cell of each image acquisition moment loaded surfaces cell wall and make a gesture of measuring A
i(i=0,1,2 .., I), as the deformation situation data of measured material in the loading procedure;
4.1) make a gesture of measuring A according to the tissue before the cytomorphosis
0Make a gesture of measuring A with the tissue after the distortion
iCalculate the whole strain stress of measured material
A, ε
A=(A
i-A
0)/A
i
3. method as claimed in claim 1 or 2 is characterized in that, after loading end, also comprises the steps:
6) take measured material continuously to the complete halted state of this measured material deformation resilience by described image acquisition units;
7) described graphics processing unit calculates any one integral thickness or length L constantly of the stressed back of measured material
kThereby, calculate springback capacity R and rebound degree R
r, R=L
k-L
0, R
r(%)=(L
k-L
0) * 100/L
0Wherein, k=0,1,2 ..., K, the moment that " 0 " representative test has just finished.
4. method as claimed in claim 3 is characterized in that, in measuring process the temperature of measured material is controlled at certain scope.
5. method as claimed in claim 4 is characterized in that, in described measuring process the water percentage of measured material is controlled at certain scope.
6. method as claimed in claim 5 is characterized in that, described loading comprises: stretch, compression, crooked, reverse or shear.
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| CN 200910089770 CN101603819B (en) | 2009-07-23 | 2009-07-23 | Real-time measurement method for wood deformation microstructure characteristics |
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|---|---|---|---|
| CN 200910089770 CN101603819B (en) | 2009-07-23 | 2009-07-23 | Real-time measurement method for wood deformation microstructure characteristics |
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| CN101603819B true CN101603819B (en) | 2011-11-16 |
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| CN104613888B (en) * | 2015-02-03 | 2017-06-13 | 清华大学 | Smog deformation of body measuring method is passed through under a kind of flame smoky environment |
| CN104897465A (en) * | 2015-06-10 | 2015-09-09 | 长安大学 | Equipment for measuring tensile deformation recovery capacity of epoxy resin joist |
| CN105334104A (en) * | 2015-09-23 | 2016-02-17 | 中国特种设备检测研究院 | Magnetic signal detection apparatus |
| CN106198249A (en) * | 2016-06-23 | 2016-12-07 | 大连盛辉钛业有限公司 | Test the method and system of medical TC4 titanium alloy ballistic properties |
| CN106644704B (en) * | 2017-03-09 | 2019-02-22 | 中国工程物理研究院核物理与化学研究所 | A kind of test method of material microdeformation |
| CN109696351A (en) * | 2019-01-21 | 2019-04-30 | 中国林业科学研究院木材工业研究所 | It is a kind of for recombinating the long-term tensile load test device of composite construction bamboo |
| CN109682818A (en) * | 2019-02-28 | 2019-04-26 | 华南理工大学 | A kind of device and method of real-time measurement cellulose or lignin material bulking coefficient |
| CN111156919A (en) * | 2020-03-10 | 2020-05-15 | 广州特种承压设备检测研究院 | Metal material micro-deformation measuring method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1800838A (en) * | 2004-12-30 | 2006-07-12 | 戚大伟 | Non-destructive test device for wood |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1800838A (en) * | 2004-12-30 | 2006-07-12 | 戚大伟 | Non-destructive test device for wood |
Non-Patent Citations (2)
| Title |
|---|
| D.Choi et al.Image analysis to measure strain in wood and paper.《Wood Sci. Technol.》.1991,第25卷251-260. * |
| Federica De Magistris et al.Deformation of wet wood under combined shear and compression.《Wood Sci. Technol.》.2005,第39卷460-469. * |
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